Intercropping potatoes in early spring in a temperate climate. 2. Radiation utilization

Three experiments on intercopping potatoes with cabbage are reported in whi ch the cabbage crop was transplanted between rows of potatoes prior to plan ting. The cabbages were removed before the canopies of the component crops overlapped, but comparison with sole crops showed that the ground cover of both crops had been retarded. This early competition affected both the amou nt of radiation intercepted by the potato crop and its efficiency of conver sion into dry matter. As a result the sum of the radiation intercepted by t he intercrops in no instance exceeded that of the sole potato crops. The ev idence suggests that largely before any significant competition for light d ue to mutual shading, competition for water, nitrogen and possibly other es sential elements, took place, with repercussions for canopy growth for the remainder of the growing season.